A. First, make an educated guess where your great-great-grandmother lived. Ask relatives and examine family papers for clues. If you come up empty, search a census database such as Ancestry.com or HeritageQuest Online's (available free at subscribing libraries). Then consult these records:

City directories: Published in the late 1800s and early 1900s for most cities and towns, these listings of businesses and residents resemble today's telephone books. Large public libraries often carry printed or microfilmed directories for nearby areas and major cities across the country, and you'll find collections on Ancestry.com and Footnote.

Court records: Your ancestor probably had to pay taxes on her property and obtain a business license. Use a reference book such as The Family Tree Resource Book for Genealogists (Family Tree Books, $29.99) to learn the location of court records from her town and era—good bets are the courthouse or state archives. And do a place search of the Family History Library's online catalog (click the Library tab). You can borrow microfilmed records to view at your local branch Family History Center.

Sanborn Fire Insurance Maps: These detailed maps helped insurance agents decide how likely a property was to catch fire. Look for them at large libraries, such as the Boston Public Library, which has microfilmed Sanborn maps from Massachusetts from the late 19th century to the 1990s. Also see Harvard's Frances Loeb Library Web site.